SAWEM and the data behind a power market
The South African Wholesale Electricity Market is the competitive market South Africa is introducing as the power sector unbundles, with the National Transmission Company of South Africa as market operator. Markets run on transparent physical data, and that is what this site measures: what the grid generates, what the country demands, and how well the forecasts hold up, every hour.
What a market participant watches
Demand sets the price shape. South African demand swings about 8 000 MW through an ordinary day, peaking around 18:00, and the time-of-day page shows the average profile a trader would bid against. Peak demand in this record was 34 666 MW on 23 June 2022.
Forecast error is where money changes hands. Over the last year Eskom's demand forecast missed by about 2.2% in a typical hour, while the renewable output implied by its planning ran 6.0% above what the fleet delivered. The forecast accuracy chart tracks both continuously, which is exactly the gap a balancing market prices.
Supply mix drives the marginal unit. When the diesel peakers run, the system is expensive; when midday solar floods in, it is cheap. The live dashboard shows which world the grid is in right now.
GridPulse ZA is independent and not affiliated with Eskom, the NTCSA or any market body. Figures are calculated from data Eskom publishes.